Container Desiccant Salt. Types and Measures

We have already mentioned this product in other previous posts on this blog. Still, we believe that it deserves a much more complete explanation of what it is, what it is used for, the types that exist and, above all, the different measures used and their equivalences, which are often confusing and unknown.

Drying salts, and dehydrating salts, are chemical compounds that absorb moisture in enclosed spaces.

They began to be used during the First World War to absorb vapors inside the masks.

In World War II, it became essential to keep certain products dry and prevent damage, such as penicillin and military equipment.

As you can see, this product can absorb water and humidity in very different ratios, depending on the amount of desiccant and its chemical composition. It can regenerate if it is subjected to a temperature higher than 150ºC.

Types of desiccant salts

There are several types of container desiccant. The most common are:

Silica gel:

They are small solid balls of silicon dioxide obtained through sodium silicate. Despite being a chemical compound, it is not toxic or flammable. However, one of its components is highly toxic to humans if ingested or in contact with it for a long time, as it could cause silicosis.

This is cobalt chloride, which determines the gel's moisture. In this way, it causes the gel to change color when wet, varying from blue (dry) to pink.

Bentonite:

It is a very fine-grained (colloidal) clay of the montmorillonite type that contains bases and iron. The name derives from a deposit found in Fort Benton, United States. 

The particle size is less than 0.03% of the average grain of kaolinite.

bentonite example

Calcium chloride:

In addition to being used in pharmacy and food, this compound is used as a desiccant, given its quality to absorb moisture.

It is less common than silica gel, despite not containing toxic elements and having a higher degree of moisture absorption. The problem is that its use is not advisable for spaces not hermetically sealed since it risks liquefying, consequently eliminating its absorption capacity.

How to measure desiccant salts

There are four different units for measuring desiccants. Grams are most used for their standardization, but we also find NFH, DIN, and MIL units. These would be the equivalences between them, taking as reference the most used measures:

Desiccant salt equivalence table

We recommend using a bag of half a kilo (16 DIN units) of drying or dehydrating salts per cubic meter. As data, we can indicate that for a 20-foot container, it is advisable to use 20 bags of 1 Kg.

These data are estimates since, depending on the load to be transported (mainly sensitivity to oxidation and/or corrosion), the proportion of salts must be adjusted to maintain the relative humidity at the established rates.

Desiccant salt container:

Desiccant can be purchased in bulk or packaged in breathable bags for use in containers or inside the packaging.

The bags are made of non-woven fabric so that moisture passes through them and can be collected by the compound. In addition, certain desiccant manufacturers have started using another material called Tyvek, mainly used to construct houses and buildings to prevent moisture.

This material is made of high-density polyethylene and non-woven olefin fiber, so it is highly breathable and has many different uses. Although however, like paper, we must not forget that it is plastic when recycling it.

As we mentioned at the beginning of this section, desiccant bags are frequently used in containers for shipping goods by sea. However, as we explained in previous blog posts, salt compounds and humidity can cause the merchandise to be damaged. For this reason, many containers come with special cables or rings to place desiccants.

In this case, a hook or hook, usually made of plastic or metal, is added to the bags to hook them to the walls of the container. If the container does not have the means to hang the bag, many manufacturers incorporate a special adhesive to stick it directly to the inner side walls.

To buy best container desiccant get in touch with Britwrap protective packaging company, as it is the best protective packaging all over the UK.

Moisture detector strips

These cards work by changing color so that when their blue color disappears, turning to light pink, as in silica gel, the drying salts have already exhausted their absorption capacity.

In conclusion, you will have to choose the type of desiccant that you think is convenient and in the right measure depending on the volume of the load and how it is packed.

It is very convenient to use since humidity is present everywhere and in certain regions and countries more than in others. Above all, it is an essential requirement for maritime and river transport, combining it with other materials for adequate protection.